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Five progressive clues
These are the case findings in their original reveal order, moving from the broader presentation to the most discriminating evidence.
Clue 1
A 58-year-old African American man hurries up to the community pharmacy counter just after it opens, speaking in a thick, slightly slurred voice and pointing at his swollen lower lip. He woke up like this about two hours ago and says it is getting worse by the minute. He is a city bus driver due to start his route soon, and he insists he feels otherwise fine, with no rash, no itch, and no trouble breathing yet.
Clue 2
The swelling came on overnight with no hives, no itching, and no obvious trigger, no new foods, stings, or detergents. He took two doses of diphenhydramine at home overnight with no improvement at all. He has type 2 diabetes and hypertension, and about three months ago his physician started a new once-daily tablet to lower his blood pressure and help protect his kidneys. He has never had an episode like this before.
Clue 3
On examination the pharmacist notes tense, non-pitting swelling of the lips and the left side of the tongue, with no wheals, no flushing, and no urticaria anywhere on the skin. Reviewing his profile, she also notices he phoned the pharmacy twice in the past month asking what to do about a dry, tickly cough that started a few weeks after his new blood-pressure tablet and simply will not quit.
Clue 4
Sent to the emergency department, his workup shows a normal serum tryptase, a normal C4, and a normal C1 esterase inhibitor level and function. His complete blood count shows no eosinophilia. There is no laryngeal involvement on exam, and he stays hemodynamically stable throughout, with the swelling neither improving with IV antihistamines and corticosteroids nor progressing to his airway.
Diagnosis
ACE Inhibitor-Induced Angioedema
Why the diagnosis fits
Non-urticarial, non-pruritic angioedema that fails to respond to diphenhydramine, combined with a new dry cough that began weeks after starting an antihypertensive used for both blood pressure and diabetic kidney protection, is the classic fingerprint of angioedema from an angiotensin-converting enzyme inhibitor. Normal C4 with normal C1 esterase inhibitor level and function is the KEY discriminator that excludes hereditary and acquired C1-INH deficiency (the other bradykinin-driven mimic), while absent urticaria and a normal tryptase rule out histaminergic/allergic angioedema and anaphylaxis. Resolution after simply withdrawing the drug (with no benefit from antihistamines or steroids) plus the higher incidence in Black patients seals it. Management is permanent avoidance of the entire drug class, not just the single agent, because cross-reactivity within the class is expected.
Educational reference
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Open the clinical referenceFor education and entertainment only. This fictional case is not medical advice and does not replace supervised clinical training, diagnosis, or treatment.